The present invention relates to methods and apparatus for transmitting power and data, and more particularly, to methods of powering devices coupled to the human body and communication information between the devices.
Small portable electronic devices are commonplace today. Small portable devices commonly used by people today include wristwatches, radios, communications devices, e.g., pagers and cell phones, and personal data assistants (PDAs) to name but a few exemplary devices. As electronics manufacturing techniques have improved, weight and power consumption requirements of many small portable devices have decreased. At the same time, the capabilities of the devices have increased. As a result, it is now possible to power many small electronic devices including watches, audio players, personal data assistants, portable computers, etc. with relatively little power.
Given the small size and portable nature of many of today""s portable electronic devices, people have begun wearing them on their bodies. For example, wristwatches are worn on people""s arms, pagers and PDAs are worn on people""s belts, and small displays are sometimes worn mounted on headgear.
As a result of carrying multiple portable electronic devices, there is often a significant amount of redundancy in terms of input/output devices included in the portable devices used by a single person. For example, a watch, pager, PDA and radio may all include a speaker. In order to reduce the redundancy in input/output devices, networking of portable electronic devices has been proposed. By exchanging data, e.g., as part of a network, a single data input or output device can be used by multiple portable devices, eliminating the need for each of the portable devices to have the same input/output device.
Various approaches have been taken in an attempt to network portable devices. The uses of radio (RF) signals, infrared (IR) communications signals, and near field intrabody communication signals are examples of various signals that have been suggested for use in networking portable devices. Radio signals between devices can cause interference. In addition radio devices can be expensive to implement and tend to consume relatively large amounts of power. In addition, decoding another person""s transmitted information and controlling another person""s device is plausible using RF, raising the concern for security and privacy. IR communications signals present similar privacy concerns to those of RF signals while further being subject to additional limitations in terms of the tendency for many objects, e.g., opaque objects, to block the transmission of IR signals. Near field intrabody communication signals represent a relatively new and still largely undeveloped field of signal communications.
In the case of one near field intrabody communications system, information is exchanged between electronic devices on or near the human body by capacitively coupling picoamp currents through the human body of a person.
While some work has been done to minimize the redundancy that exists in data input/output devices, in portable devices frequently used by a single individual, there still remains room for improvements in the way information is communicated between portable devices. In addition, some wearable devices are not big enough to have any kind of interface at all; e.g. earrings.
There remains significant room for improvement with regard to how portable devices are powered. Portable electronic devices frequently rely on power supplied by batteries to operate. Batteries have a limited energy storage capability. As a result, batteries periodically need to be replaced or, assuming they are rechargeable, recharged. The need to replace or recharge batteries posses a serious limitation on known portable battery powered devices. Battery replacement normally involves physically removing a current set of batteries and replacing them with a new set of batteries. Recharging of batteries normally involves plugging the portable device into a battery charger thereby limiting the devices portability until the re-charging is complete or, alternatively, swapping a charged battery pack for a battery pack including the batteries, which need to be recharged.
The swapping of battery packs, replacement of batteries, and/or recharging of batteries by plugging in a portable device represents an inconvenience in terms of time involved with a user performing a battery replacement operation or recharging operation. In many cases it also represents an interruption in service, i.e., often during the battery swapping or recharging operation, the device cannot be used or its portability is limited.
Until the present invention, the focus with regard to portable device power issues has been largely on improving the quality of batteries, reducing the amount of power required by a portable device to operate, and/or in providing backup power sources, e.g., to permit the swapping of batteries without causing an interruption in operation.
While recent improvements in batteries and device power consumption has increased the amount of time portable devices can operate before needing the batteries to be recharged or replaced, the need to periodically recharge or replace batteries in portable devices remains an area where improvements can be made. In particular, there is a need for making recharging of batteries easier to perform, preferably without requiring an interruption in device operation or for backup batteries inside the device. There is also a need for eliminating batteries in at least some portable devices, thereby reducing the weight of the portable devices making them easier to wear for extended periods of time.
The present invention is directed to methods and apparatus for distributing power to devices coupled to the human body. The invention is also directed to methods and apparatus for communicating information, e.g., data and control signals, to devices coupled to the human body.
In accordance with the present invention the human body is used as a conductive medium, e.g., a bus, over which power is distributed. Information, e.g., data and control signals, may also be distributed over the human body in accordance with the present invention. To avoid the need for digital circuitry, e.g., in audio output devices, some of the communicated signals may be analog signals. For example, analog audio signals may be transmitted to a speaker using the human body as the communications media by which the audio signal is transmitted.
In accordance with the invention, power is distributed by coupling a power source to the human body via a first set of electrodes. One or more devices to be powered, e.g., peripheral devices, are also coupled to the human body via additional sets of electrodes. The devices may be, e.g., a speaker, display, watch, keyboard, etc. A pulsed DC signal or AC signal may be used as the power source. By using multiple power supply signals of differing frequencies, different devices can be selectively powered. For example, a 100 Hz signal may be used to power a first device while a 150 Hz signal may be used to power a second device. Digital data and/or other information signals, e.g., audio signals, can be modulated on the power signal using frequency and/or amplitude modulation techniques. The power source and peripheral devices can interact to form a complete computer network where the body serves as the bus coupling the devices together. Devices can include optional batteries, one or more CPUs, transmit/receive circuitry, and/or input/output circuitry. In one particular exemplary network implementation the first device to be placed on the body operates as a master device, e.g., bus master, with subsequently added devices working as slaves. In accordance with the invention power and/or communication signals may also be transmitted from one body to another by touch.
The proposed methods of the present invention enable the use of a whole new class of wearable devices. These devices do not have a direct interface, but are instead used as relays for collecting and transmitting information to the user. For example earrings, which can be used to measure the persons pulse rate or even deliver sound to the ear via a phone worn on the person""s belt. To program the earring directly would be a quite cumbersome task; however, the earrings parameters could be set via another device that is large enough and has the appropriate user interface to enter data. The user could use this device to control the volume of the earrings or to control other function of this device. This concept could be extended to many other such devices that are worn on the body: jewelry, watches, and eyeglasses to name a few.
Because the devices of the present invention are networked, they can be recharged and powered by other devices on the network. Kinetic to power converters can be used in this network to sustain this network""s power. Kinetic converters in shoes and on wrist watches can be used to convert the kinetic energy of the user to electrical power and distribute that power to the rest of the network. This is yet another property that distinguishes devices of the present invention from other networks such as RF or IR.
Numerous additional features and advantages of the present invention will be discussed in the detailed description, which follows.